THE VITALITY AND DISTRIBUTION OF SEEDS 
305 
and air. Almost immediately after the clearance, the ground becomes 
carpeted with a grand show of Primula vulgaris (or, in one district, 
P. elation ), Scilla nutans, Anemone nemorosa, Lychnis diurn a , and 
other species of woodland plants. As the underwood again grows up, 
these plants gradually become depauperated. Primrose plants with 
etiolated leaves, scarcely recognizable, may often be found in the 
thick undergrowth. 
These woods should afford an admirable opportunity for experi¬ 
mental research. It is suggested that if a series of samples of the 
soil were taken from different depths, and also from each of the 
sections of the wood, and the vitality of the seeds carefully tested, 
some valuable results might be obtained. Possibly the proportion of 
seeds retaining their vitality, found in each section, might be shown 
to be directly proportional to the length of time which had passed 
since the section had been last cleared. The thick covering of the 
ground by the undergrowth of wood would certainlv have afforded 
good protection from the access of seeds of a more recent date. 
It would appear that we can scarcely claim that this ancient 
problem has been definitely solved; yet a consideration of recent 
researches leads to the conclusion that we have arrived at a probable 
solution of the riddle, and that some carefully devised series of experi¬ 
ments might carry us to the desired goal. In some of the cases, the 
areas upon which the alien plants appeared had evidently been well 
supplied with seeds from the near neighbourhood, within measurable 
period of the time when the crop of plants suddenly sprang up. We 
have also much evidence that the seeds of wild plants frequently 
retain their vitality for a sufficient length of time to enable them to 
take advantage of any favourable opportunity for germination. 
Observations such as those suggested in connection with JJlex 
and Tropceolum majus should add much to our knowledge ; and 
experiments as to the distribution of seeds in sufficient quantities to 
explain their abundance in excavated soil, in river-dredgings, and in 
geological strata might lead us to more definite conclusions. 
The following experiments are suggested as likely to give fruitful 
results :—A dock of sheep or herd of cattle, after pasturing in a field 
open to the free seeding of trees or herbaceous plants, might be 
removed to an area proved to be quite free from these particular 
seeds. After a limited period, the soil from the latter area could be 
carefully washed and sifted, and the number of seeds found to be 
transported estimated. Open-air experiments under natural con¬ 
ditions, such as the exposure of adhesive plates to catch drifting, 
seeds, should afford us valuable information as to the distance to 
which seeds are carried from any given source. Other experiments to 
trap the seeds carried by flowing streams or tides, or by animal 
transport ( e.g ., by birds or the smaller mammals), could be easily 
devised and should afford much that is of interest regarding the 
subject of sporadic floras. 
I wish to record my indebtedness to Mr. A. Gepp for suggestions 
and encouragement in the preparation of this paper and for supplying 
me with many references to the literature of the subject. 
